Hi , Great project with a great write up. Im based in the uk. Ive also got a pearl white b4Q saloon running the later 40v 4.2 v8 from a c5 s6. Ive picked it up as a part running project and been trawling the US forums for info as there is very little on this conversion over here. Everything is up and running. It goes ( quickly) and stops but the conversion is very agricultural. My plan is to make it as factory as possible. Interesting info on the cooling. Mine has mix mash of pipework and using the stock 2.6 rad with 3 slimline fans with a separate two stage controller running two of the fans. However the in dash gauge is showing 121deg constant. Need to get it plugged into vcds and get a true reading. Power steering groans like hell. Ive tried 2 different dual vane v6 pump but the droan is still there. Will look at converting to vacuum brakes / steering and try to use the s6 pump. Also has a miss when hot on WOT, think this might be a failing coilpack. Again need to have a look on vcds

Sorry for the hijack. Will keep following this and see how you get on All the best Gav

Gav wrote:Hi , Great project with a great write up. Im based in the uk. Ive also got a pearl white b4Q saloon running the later 40v 4.2 v8 from a c5 s6. Ive picked it up as a part running project and been trawling the US forums for info as there is very little on this conversion over here. Everything is up and running. It goes ( quickly) and stops but the conversion is very agricultural. My plan is to make it as factory as possible. Interesting info on the cooling. Mine has mix mash of pipework and using the stock 2.6 rad with 3 slimline fans with a separate two stage controller running two of the fans. However the in dash gauge is showing 121deg constant. Need to get it plugged into vcds and get a true reading. Power steering groans like hell. Ive tried 2 different dual vane v6 pump but the droan is still there. Will look at converting to vacuum brakes / steering and try to use the s6 pump. Also has a miss when hot on WOT, think this might be a failing coilpack. Again need to have a look on vcds

Sorry for the hijack. Will keep following this and see how you get on All the best Gav

Sweet project. I have a friend thinking about putting a belt driven Audi V8 into a B3/B4 chassis! Are you using the stock ECU? Retrofit the accelerator pedal into the B4 for drive by wire? How does it run?

Third (current) ECU :1999, A8, with reflect tuning chip and immo, ran ok. Similiar to first ECU, but maybe even worse, as I can't find that sweet spot where it would accelerate quickly. I dont know how the immo device would effect any of this, but its either that or the chip I installed. I had it done by a guy I work with who has been doing stuff like this for years, so I am confident it was installed correctly. Before the reflect chip was installed the immo device was not needed. The chip, is based off of a euro file which apprently needs the immo device.Never scanned. My next step is to scan this current ECU.

Might end up trying to find another 1999 ECU and just run it stock. I'm thinking there are some differences ECU and/or hardware wise between different model year ABZs.

I've been training for a half ironman, so car stuff has been on the backburner, severely.

Have put this project off to do other things, until about a week ago when I decide oh shit lets go to Carlisle...

Figured out a few thing on the cluster but still can't get the temperature gauge to work. From what I can tell the blue/brown wire (pin 2, I think) on the black connector going to the cluster should go to the T connection on the temp sensor from the V6. I tried doing that offline, grounding the threads, heating up the sensor and running the wire right to the sensor. Gauge doesn't move.

Any insight on this? I also tried using the ABZ sensor that goes to the gauge but it seems a bit different. I could really use a pointer on how to get this functioning!

Lastly, I never had a speed signal going to the ECU... which might be why acceleration stuff was scewy with some ECUs? @the german, did you need to run that to the ECU?

I had a similar issue with the temp sensor on my ABH/ABZ hybrid CQ. I ended up with the thought that whatever temp sensor the cluster is looking for needs to be put on the engine. The CQ (and I think the B4) use a MFTS with 3 or 4 prongs rather than the 1 or 2 prong sensor the ABZ uses. Do you have a wiring book for the B4?

I mean vehicle speed. The car won't run without engine speed, but like I said in a post above I get some weird behavior with different ECUs and the only one that works well-ish is a stock 1999. I'm going to give it a shot, it's not hard to hook up. It would be awesome it it fixed my chipped ECU issues.

As far as the coolant temp goes, I had the wiring correct on the 4 wire ( updated part has 3) multi function coolant switch. My cluster was not working right though. Luckily I has a spare and swapped it in, I was able to get a reading from the original sensor by heating it up offline, grounding the threads and running the blue/brown wire from the clutster to it.

I decided to try to use the OE ABZ one ( front of the engine, right side when looking at the front of the car) by running my cluster wire (regulated 10v blue/brown) to the sensor and unlike the V6 sensor this one has a dedicated ground. To my joy it worked, the gauge reads a little higher than the normal V6, but I can easily run vagcom and match the tick marks to actual temperatures.

All in all it's coming together, also got the car inspected today which is a huge deal. The last one expired in 2017...

Well I am getting the code P0501 - which is a vehicle speed sensor range/performance issue. And I'm thinking the TCU may have sent over speed, which I don't have anymore. Even on the older stuff the instrument cluster has a 'speed out' to the ECU, the V6 the was in this thing before even had this. ( I am looking now and can't find the diagram I saw this on , but I will find it! )

While those diagrams are great, I had alldatadiy at some point for this car and those diagrams were much more complete. I'm going to have to buy a bentley or get the all data again.....